The worldwide distribution and extensive genetic diversity of the whitefly Bemisia tabaci has long been recognized. However, whether B. tabaci is a complex species or a species complex has been a subject of debate. Recent phylogenetic analyses suggest that B. tabaci is a cryptic species complex composed of at least 24 morphologically indistinguishable species. Here, we conducted crossing experiments and demonstrated reproductive incompatibility among three of the 24 putative species. Our data and those of previously reported crossing experiments among various putative species of B. tabaci were collated to reveal the pattern of reproductive isolation. The combined results provide strong support to the proposition that B. tabaci is a cryptic species complex.